friends were invited. For this occasion he prepared, with my help,
to perform for the girls and boys some electrical experiments, and
particularly to give all who chose to try it an electric shock. For
this purpose he had them all join hands, and the electric charge was
sent through the whole line at once. One thing he did shocked his
mother more than anything else. He instituted a mock court, at which
one of the boys was tried, convicted and condemned to be executed by
electricity. The whole affair was enacted with no great solemnity, but
the electrical experiment was voted a great success by the executed
"criminal." The following group of experiments, however, seemed to give
the most satisfaction: On a table was placed the coherer connected to
the relay, and in another room was placed the spark coil for sending
ether waves. He had this operated by a confederate whom he chose for
the purpose. He then connected two wires to the relay, one at _d_ and
the other at _e_ (Fig. 189). These ran to a battery cell and a bell in
a far corner of the room. At a given signal (a cough) the confederate
made a spark at the spark coil in the other room; this sent ether
waves through the partition between the rooms; the ether waves caused
the coherer to pass electricity from the dry cell No. 1, to close the
relay spring _R_. This acted like a switch to close the second circuit
through the dry cell No. 2 and the bell, which rang out to the surprise
of all. It continued to ring until he tapped the coherer tube and broke
apart the filings. When this had been tried to the satisfaction of all,
the company was invited to another room. Here they found an electric
train with tracks, train sheds, stations, tunnels, bridges, switches,
signals, etc., arranged upon a centre table. The electric train was to
be started by ether waves. A wire from the railroad track was connected
with _e_ of the relay (See Fig. 190). A wire from _d_ of the relay was
connected to the third rail through a battery of sufficient strength
(Battery 2). The electric train completed the circuit by connecting
the tracks with the third rail. All heard the crack of the spark coil
in the adjoining room, and saw the train start immediately. Ether
waves had caused battery 1 to close the relay _R_. This had closed the
circuit so that battery 2 might run the train, of course by means of a
motor in the train. He tapped the coherer. The relay spring _R_ flew
open and the train stopped. Presently another crack from the adjoining
room, and the train instantly started again. When all the details of
the electric train had been examined the company was invited to go to
the dining room, which was dimly lighted by candles. All were seated
and busily conversing when the crackling noise of the spark coil was
again heard, and a group of little electric lights flashed forth upon a
birthday cake. The wires from the lamps and a battery to run them had
been connected with the binding posts _d_ and _e_ of the relay.
[Illustration: Fig. 190]
The chandelier over the dining-room table had a pendant push button
_A_ (Fig. 191), with which the regular electric lights could be turned
on and off. This I had removed and extended the wires down upon the
table. It was only necessary to connect these to the binding posts _d_
and _e_ of the relay, and the next wave from the spark coil lighted the
chandelier.
[Illustration: Fig. 191]
The flexible wires underneath the dining-room table with which the
maid is usually summoned from the kitchen were next extended up and
connected with _d_ and _e_ of the relay, and the maid was called in
by an ether wave. She brought with her a tray in the centre of which
stood an earthenware cup, such as is used for baking custard. This had
been filled with a mixture of granulated sugar and powdered potassium
chlorate. Four dry battery cells stood around this upon the tray
connected in series (Fig. 192). A very small iron wire connecting
two of these cells dipped into the sugar mixture. Two wires from the
battery were connected to _d_ and _e_ of the relay. At the proper
signal an ether wave was sent out by the spark coil. The coherer closed
the relay and the relay acted as a push button to close the circuit of
the four cells upon the tray. The fine wire dipping into the sugar and
potassium chlorate got red hot. This caused the mixture to flash up and
burn in most beautiful coloured flames. (Fig. 193).
[Illustration: Fig. 192]
[Illustration: Fig. 193]
On this occasion Harold's friends gave him, with due formalities,
the degree of E. E., which they said meant _electrical expert_, and
ever since that night he has been called "the expert." I inquired of
the young folks, as their party was breaking up, if they understood
Harold's explanations of all these things, and he replied that he at
any rate understood them better having attempted to explain them.
XXIII
TELEGRAPHING BY ELECTRIC WAVES
The next time Harold and I experimented we arranged something to save
us the trouble of tapping the coherer each time we used it. We employed
simply an electric bell, _B_ (Fig. 194), from which we removed the
gong. By reference to the figure the arrangement will be understood.
Each time ether waves cause the metal filings to cohere and the battery
_B^{1}_ closes the relay _R_, battery _B^{2}_ causes the hammer of
_B^{3}_ to tap against the coherer. This causes the current to cease to
flow from _B^{1}_ and the relay opens again by its own spring.
[Illustration: Fig. 194]
[Illustration: Fig. 195]
Our next addition was a telegraph sounder as shown in Fig. 195. _B^{1}_
is a single dry cell, _C_ is the coherer, _R_ is the relay, _B^{2}_ is
now a battery of three cells. Part of its current goes to _B^{3}_,
the tapper for the coherer, and part of its current goes to the
electro-magnet of the telegraph sounder _S_. Ordinarily a spring holds
the iron strip _d_ up against the metal stop _a_, but when the current
passes through the electro-magnet it pulls down this iron strip with
a click against the metal stop _e_. But while this is happening _C_
is being tapped by _B_, and is ready to respond to each wave. It was
only necessary now to have some code of signals in order to communicate
by telegrams. We learned the system of dots and dashes, or short and
long periods marked off by the sounder, which all telegraphers use
and which is known as the Morse alphabet, and very soon Harold and
I were telegraphing from one room to another messages of several
sentences at a time, the Morse alphabet being told off on the spark
coil and being received through the coherer and telegraph sounder.
It was not long before Harold and one of the neighbours' boys were
exchanging messages between their homes, each having a spark coil and
the necessary receiving apparatus, and having extended their antennæ to
the top of the buildings into what are called in the wireless language
_aerials_.
[Illustration: Photograph by Helen W. Cooke. Induction Coil of a
Wireless]
The fever for wireless telegraphy spread like wild-fire among the boys.
In a few months they had formed a "wireless club." They had each read
anywhere from ten to thirty books and articles upon the subject, and
had secured the latest improved apparatus. They made it a practice
to spend hours daily at their instruments picking up and keeping on
file messages which were sent to and from steamers leaving the harbour
for European ports. On one occasion they showed me from these files
scores of messages--fond, personal, and supposedly private farewells to
friends and communications between business partners which they would
never have made on land without first closing the office door. The
boys had acquired a mass of technical knowledge upon the subject which
far exceeded my comprehension. But their teachers in school complained
that they would learn nothing else, and some of the boys had already
received warning that they might fail of promotion.
How to have compelling interests without riding hobbies is the great
problem for both boys and men. I have known many boys who could, or at
least would, do nothing well in school or out, except some specialty
like manual training or science. In later years they were so deficient
in education that they could hold no worthy position in anything. My
anxiety was to save my boy from such a fate. I was determined that he
should have a fair share of all kinds of culture. To this end we read
together much of biography, history and classical literature, ancient
and modern, through the medium of the English language.
As both prevention and cure of the wireless telegraph mania I deemed
it not necessary to suppress enthusiasm, nor to introduce obviously
useless tasks for the sake of the training which might be in them.
My method was, on the contrary, to encourage my boy to have several
hobbies which he might ride with enthusiasm, but to make it a rigorous
rule to exchange his "mount" occasionally.
XXIV
HALLEY'S COMET AND ELECTRICAL WAVES
[Illustration: Fig. 196]
It was the year 1910 and Halley's comet was approaching the sun. On
May 18 its tail might be expected to reach the earth. Astronomers had
requested all who might be possessed of wireless telegraph apparatus
to watch on that day for any peculiar behaviour of their apparatus so
that evidence might be obtained whether or not the comet sends forth
such ether waves as we call electricity. Harold desired me to explain
the whole matter to his group of friends, which I did on a subsequent
evening, as follows:
"Although Halley's comet has come within the earth's orbit about three
thousand times since its first recorded appearance, I know of no man
living who can give a satisfactory account of having seen it. Any one
who has seen it before must be at least seventy-five years old, for
it requires seventy-five years to make one complete circuit of its
own orbit. But no one who is now seventy-five could have observed it
intelligently, and even one who is now eighty-five years old would
have to tell what he saw when he was ten years old and has remembered
for seventy-five years. Furthermore, any account of how it looked on a
former return is no guide to how it may appear on this trip. You may
properly think of the comet as a group of solid pieces no bigger than
the stones you may throw, scattered, two or three to the mile, through
a space 12,500 miles broad. This extremely thin cloud of particles does
not reflect enough sunlight to be visible, even in a telescope, in
any part of its journey, and hence we should be wholly unaware of its
existence if it did not sometimes have the strange faculty of giving
out light of its own _while in that part of its own orbit nearest to
the sun_. At such a time there is a hazy light enveloping the mass of
small bodies, and streaming away sometimes many million miles from
them. The mass of small bodies is generally referred to as the nucleus,
and the stream of luminous gas which the nucleus gives forth is called
the tail, though it reminds me more of a search-light.
"It does not trail along behind the comet but always points away from
the sun (Fig. 197). The normal thing for a comet to do is to begin to
develop a faint light and a short streamer as it gets near to the sun,
to have its light grow brighter and its streamer to grow longer until
it reaches the point nearest the sun, and then to have its light grow
dimmer and the streamer grow shorter as it recedes from the sun.
[Illustration: Fig. 197]
"It has many times been suggested that this strange search-light
appearance may be an electrical phenomenon, some form of ether waves
which the comet sends forth when under the immediate influence of the
sun. But not all comets are alike in this matter, nor does the same
comet always act alike on succeeding trips, so that we may not predict
what Halley's comet will do on this visit. It would be natural to
suppose that Halley's comet, like radium, might in time lose the power
to radiate off material, in which case it might at length become wholly
invisible to us, even though it continued to travel in its wonted
path. Our only way of knowing of its existence then would be that on
its returns some of its small pieces might be attracted to the earth
and enter our atmosphere as meteors. This sort of thing is continually
happening, and may be the last reminders of once brilliant comets.
"For almost a century it has been the common belief that light is
merely a wave motion in the ether. Our eyes respond to ether waves of
certain length only. Waves a little longer than those which affect
our eyes are felt by us as heat waves. Waves still longer than those
of heat are the so-called electric waves. These we use in wireless
telegraphy. There are still shorter waves than those of light. These
affect the sensitive plate in photography. They help to form the green
material in the leaves of plants and the brilliant colours in flowers.
They assist in the fading of our clothes and the tanning of our skin.
These are called chemical waves. Still shorter waves in the ether than
those of which we have just spoken are the X rays, and all the strange
things which they may do have not yet been determined. Certain it is
that they can make dreadful sores in our flesh. They can penetrate
through wood and paper, but not metals. They pass readily through
flesh, but not bones. All such ether waves are treated in a book by
Sylvanus P. Thompson, entitled 'Light Visible and Invisible,' in which
he points out that electricity, heat, light, chemical rays, etc., are
all alike in being ether waves, and this was suspected by James Clerk
Maxwell and others half a century ago, and has come now to be quite
generally believed.
"Halley's comet, already having been _seen_ upon this return, must
be sending out those ether waves which we call light; whether it is
also sending forth some of the other kinds of ether waves may yet be
determined."
My audience being chiefly composed of those persons who were present
at Harold's birthday party, they pressed me to tell them more about
wireless telegraphy and similar matters, and so I agreed to give them
at some future date some account of the history of these ideas. But my
present purpose was to start an interest in astronomy as an antidote
for the wireless epidemic, and so I invited all who desired to do so to
come again one week from that evening, bringing with them such opera
and field glasses as they might be able to secure. I promised to
show them how to make a telescope such as Galileo had more than three
hundred years ago. I agreed to go out with them several evenings and
scan the sky with our telescopes, and to tell them of some readable
books and articles upon astronomical matters.
XXV
HOW THE IDEA OF A UNIVERSAL ETHER DEVELOPED
The evening for the meeting of the Science Club had arrived. Its
membership had increased tenfold within a year. At its monthly
meetings, which were open to the public, an audience of two hundred,
old and young, was usually present--a number about three times that of
the regular membership. General science was now the study of this club.
At its weekly meetings, which only members attended, the studies of
specific topics by individuals, oftentimes illustrated by experiments,
were reported. These meetings were held in one of my laboratories,
while the open monthly meeting was always held in my lecture room, with
some rather famous speakers to instruct the audience. An enthusiastic
friend of science had given a fund with the stipulation that we should
engage the services of those who both knew their subjects and had
acquired the art of presentation. The fund was $10,000 and it yielded
$500 a year. I think beyond question it was doing more for science
than any other fund of ten times that amount which can be mentioned.
On the particular evening of which I am about to speak, the lecturer
told the members of the Science Club frankly how, beginning at the
age of thirteen, he had spent forty years of _enjoyment in study_,
that he had always found great satisfaction in the study of ancient
civilizations and literatures. He had been fortunate, he said, in
having teachers early in life who could make these subjects full of
meaning to him. His greatest satisfaction, however, during the last
twenty-five years had been found in tracing the development of modern
science, both in the evolution of its theories and in its applications
to modern industries. He said he was sure that young people of
high-school age would find it profitable to learn, for instance, how
the modern theory of combustion had developed slowly through the
centuries, even if to do so they must curtail somewhat their study
of how Greece and Rome developed and declined. He said that science
furnished a tremendously rich field of study for young people, which
as yet had been untouched by our schools, first, because educational
conservatism had made it impossible to determine the relative
importance of subjects of study, and, second, because education in
science had, for a brief period, found its worst enemies within its
own camp. He would like especially to commend on this evening some
historical studies in science, and had chosen for his subject, "How the
Idea of a Universal Ether Developed."
Men seem to talk freely now about the transmission of light, heat, and
electricity by means of the _ether_. How did this idea arise? Is it a
product of wild imagination? or did the idea develop out of experiences
which, if given to any person of fair intelligence, would yield the
same result?
A little over thirty years ago, at the Royal Institution of Great
Britain, James Clerk Maxwell (1831-1879) delivered a lecture on "Action
at a Distance." It was no new subject, but rather one of the oldest and
most often discussed subjects from the days of the ancient Greeks down
to the present. We talk of gravitation as an attraction or pull between
the various bodies of the universe, but how can they pull one another
without some material bond between? This was Sir Isaac Newton's great
puzzle which he never solved, though he expended upon it the greatest
efforts of his great intellect.
The sun appears to repel the tail of the comet, yet how can there be a
push without intervening material with which to push? When we speak of
light pouring or streaming in, do we think of it as a substance? When
we speak of warm bodies losing heat, or when we cover them to keep the
heat in, are we thinking of heat as a substance? What are heat, light,
electricity, magnetism, and gravitation?
These are no new questions. They are certainly older than history.
Various ideas have prevailed at different times. It is much easier to
change our ideas than to change our language. You occasionally see and
hear the words calorie and caloric used in connection with heat. They
stand for an idea, abandoned for three generations, that heat is a
substance called caloric, which saturates warm bodies and drains out
of them when they cool off. I hardly think these ideas either arise
or fall without good and sufficient reason. Each theory has been the
natural conclusion from our observations of nature as far as we have
gone with them. To be sure, it is difficult for us to see how men
acquired, from any observations of nature, the idea of light which
seems to have prevailed previous to the time of Aristotle, three and
a half centuries B.C. This idea was that objects were made visible by
something projected from the eye itself. Still, the questions which I
have indicated regarding heat, light, and electricity have impelled
men for many centuries to observe nature for hints as to the answers.
The doctrine of the universal ether as a medium for transmitting wave
motions, and of light, heat, and electricity as being motions of
different wave length, is the natural conclusion of the present time.
It may give place to another theory when we have further facts to
reason upon. Imagine your never having seen a harp or other musical
instrument. Would it require a long time, do you think, for you to
find out its use, at least to this extent, that it will produce tones
whenever the strings are made to vibrate? That the short strings
vibrate more rapidly than the long ones, and at the same time produce
tones of a higher pitch? Imagine that having become familiar with
the harp you should successively come upon scores of other musical
instruments of very differing types. You would soon become adept at
divining their uses. Now, a study of the microscopic structure of the
eye, for one thing, would suggest that light may be in the nature of a
vibration. Scores of other lines of study in a similar manner have at
length brought all who pursue them to the conclusion that light is a
form of vibration.
Robert Hooke in England (1631-1703) and Christian Huygens in Holland
(1629-1695), back in the seventeenth century seem to have been the
first to give expression to this idea, which was nothing more than
an inkling in Hooke's mind, but which was the necessary result of
observations on the part of Huygens. For nearly a century the idea lay
dormant, largely because Sir Isaac Newton (1642-1727), the cleverest
thinker of his time, opposed it. It was perhaps unfortunate for the
success of the theory that Huygens, its founder, adopted the word
ether, for that was an old term, and had been very badly overworked.
The word ether, or æther as it was often written, had been invented
in the days of ignorance, for such foolish reasons as: (a) because
"nature abhors a vacuum," or (b) "for planets to swim in," or (c) "to
constitute electric atmospheres and magnetic effluvia," or (d) "to
convey sensations from one part of our bodies to another."
"When we remember," says Maxwell, "the mischievous influence on science
which hypotheses about æthers used formerly to exercise, we can
appreciate the horror of æthers which sober-minded men had during the
eighteenth century."
Newton in England (1642-1727) and Laplace in France (1749-1827) stoutly
opposed the undulatory theory of Huygens and championed a corpuscular
or emission theory, that light-giving and heat-giving bodies emit a
subtile fluid.
There is no other instance in the whole history of modern physics in
which truth was so long kept down by authority. Fresnel (1788-1827)
and Arago (1786-1853) in France appear to be the only persons during
the eighteenth century who caught a clear vision of the truth of the
undulatory theory.
But it remained for Mr. Thomas Young (1773-1829), a colleague of Sir
Humphrey Davy at the Royal Institution, in his Bakerian lecture (1801)
on "Theory of Light and Colour" to bring together such good evidence
for the ether wave theory that it has hardly been questioned since.
Young, like Davy, was a most remarkable man in literature and in
science. It was he who first deciphered the Rosetta Stone, now in
the British Museum, and gave us a key to the Egyptian hieroglyphics.
Probably he was the only man who was able to overthrow the influence of
Newton's authority even a century after Newton did his work.
Faraday's (1791-1867) chief work as director of the laboratory of the
Royal Institution, London, was a study of ether phenomena, particularly
electric and magnetic. About seventy-five years ago he became
impressed with the fact that although wires may give direction to an
electric current the electric influence is not confined to the wires,
but may permeate more or less widely the region about them.
Nearly fifty years ago Maxwell (1831-1878) professor of physics at
Cambridge University, England, conceived the idea that light is
electricity of a very short wave length.
Nearly twenty-five years ago Heinrich Hertz (1857-1894), in Germany,
proved by experiments the existence of electric waves, and measured
their length and velocity, determining their various characteristics as
compared with light.
About fifteen years ago Marconi developed a wireless telegraph
apparatus, which made it possible to use electric waves for purposes of
communication.
Thirteen years ago (1897) the first wireless telegraph company was
formed. Eleven years ago (1899) the international yacht races in
New York Harbour were reported by wireless telegraph, and bulletin
boards in New York City announced to waiting crowds the details of the
race while it was in progress. Nearly ten years ago (1901) wireless
despatches were first sent across the Atlantic Ocean. Wireless
telegraphy was opened for public use in 1905, and very soon the company
began to coöperate with the regular telegraph companies. Nearly all
coastwise and trans-Atlantic steamers are now equipped with wireless
telegraph outfits, and a law has passed both houses of Congress
making it obligatory on the part of steamers which carry fifty or
more passengers to have such equipment. On several disabled steamers,
notably the _Republic_, loss of life has been averted by the wireless
emergency call for help, to which the captains of all steamers feel
obliged to respond. If you desire to communicate with a friend who
left for Europe several days ago, you simply write him a telegram,
addressing it to his ship, and deliver it at your nearest telegraph
office. Each telegraph office has a record of the location of every
ship having a wireless telegraph outfit. It despatches your message to
the wireless station along the coast which is nearest to your friend's
steamer, and from this station it is sent on the ether to the ship.
Or in some cases it may be repeated from one ship to another along
the Atlantic highway until it reaches the desired one. Thus also news
of important events on either continent is distributed daily on board
ships which are crossing the ocean. There are said to be more than
50,000 amateur wireless stations in the United States, and already
Congress is taking steps to regulate the use of the wireless telegraph
in order to prevent interference with Government and other important
messages.
More than three dozen books and countless magazine articles have
already been written upon wireless or ether wave telegraphy. Hundreds
have and thousands are contributing to our knowledge of ether wave
phenomena. If the names of all who have said or done something to
render stable the foundations of this idea of a universal ether, whose
undulations account for the phenomena of heat, light, and electricity,
were to be mentioned, the list would contain nearly all the important
workers in the field of physics for the last century.
XXVI
ELECTRIC CURRENTS CANNOT BE CONFINED TO WIRES
Harold said that if electricity was so much like light that it could
go without wires he thought light ought to be enough like electricity
to be conducted by wires on occasions. I told him that I had no hope
of being able to confine light to a wire; indeed, if the Science
Club would give me an opportunity I would show them that even when
electricity follows the general direction of a wire its influence
is not confined to the wire. As a result of this bid I received an
invitation to address an open meeting of the Science Club.
[Illustration: Fig. 198]